The objective of the proposed research are to more specifically define the endocrine and neuroendocrine control of LH release in the hamster. Silastic capsules will be used to administer controlled amounts of steroids to intact and ovariectomized animals to ascertain the involvement of these compounds in feedback control of gonadotropins. Stereotaxic deafferentation and lesioning of discrete areas of the brain will allow a better assessment of specific areas involved in the positive and negative feedback action of steroids. Gonadotropins, Gn-RH and steroids will be measured in serum and tissue by radioimmunoassay. These experiments are designed to provide new information on rodent reproductive physiology and to serve as experimental models for our studies in primates.